2006A&A...456..929S

We derive black hole masses for a sample of about 300 AGNs in the redshift range 0<z<2.5. We use the same virial velocity measure (FWHM Hβ_BC) for all sources which represents a significant improvement over previous studies. We review methods and caveats for determining AGN black hole masses via the virial assumption for motions in the gas producing low ionization broad emission lines. We derive a corrected FWHM(Hβ_BC) measure for the broad component of Hβ that better estimates the virialized line emitting component by comparing our FWHM measures with a sample of reverberated sources with Hβ radial velocity dispersion measures. We also consider the FWHM of the FeIIλ4570 blend as a potential alternative velocity estimator. We find a range of black hole mass between logM_BH∼6.0-10.0, where M_BH is in solar masses. Estimates using corrected FWHM(Hβ), as well as FWHM(FeII) measures, reduce the number of sources with log M_BH>9.5 and suggest that extremely large M_BH values (logM_BH>10) may not be realistic. Derived L/L_Edd values show no evidence for a significant population of super-Eddington radiators especially after correction is made for sources with extreme orientation to our line of sight. Sources with FWHM(Hβ_BC)≲4000km/s show systematically higher L/L_Edd and lower M_BH values than broader lined AGNs (including almost all radio-loud sources).